This invention relates to a tamping labeler and to a labeling apparatus having tamping labelers.
Products to be sold are commonly labelled. In this regard, automatic labelling apparatus may be employed where the products are smaller and processed in large volumes. One approach in this regard is to wipe a label onto each product as its passes a labelling head. This approach, however, is only well suited for labelling products of uniform dimensions. Where products have irregular dimensions, such that the distance between a given product and the labelling head will vary, tamping labellers are typically used. U.S. Pat. No. 5,829,351 to Anderson discloses such a labeller. In Anderson, a turret carries a number of flexible pneumatic bellows about its periphery. The turret has a vacuum plenum and a positive pressure plenum. The turret rotates each bellows, consecutively, to a labelling station. A bellows normally communicates with the vacuum plenum which keeps it in a retracted position; also, due to end perforations in the bellows, the negative pressure holds a label at the end of the bellows. However, when the bellows reaches the labelling station, it is coupled to the positive pressure plenum which causes a one-way valve to block the perforations and causes the bellows to rapidly extend until it tamps a product below. The force of the tamping forms an adhesive bond between the pressure sensitive adhesive of the label and the product. Labels are fed to each bellows from a label cassette with a label web comprising serially arranged labels on a release tape.
A tamping labeler is suited to the labeling of produce, given the irregular dimensions of produce. However, if the produce is wet, the tamping face of the bellows will also become wet. This can result in the surface tension between the bellows and a label being stronger than the tack adhesion between the produce and the label when the label is tamped against the produce. Should this occur, the label may remain on the bellows. This event may be repeated, such that the bellows may become clogged with a plurality of labels, thereby requiring operator intervention. Even if a bellows does not become clogged, the effectiveness of the labeler is diminished if some labels do not adhere to the produce.
This invention seeks to address this problem.